MICRF113 查看數據表（PDF） - Micrel
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MICRF113 Datasheet PDF : 21 Pages
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Micrel, Inc.
Functional Description
Figure 3 is a functional block diagram of the MICRF113
transmitter. The MICRF113 is best described as a phase
locked transmitter. The MICRF113 system is partitioned
into five functional blocks:
• Crystal oscillator
• PLL×32
• Power amplifier
• Enable control
• Undervoltage detection
Crystal Oscillator
The reference oscillator is crystal-based Pierce
configuration, designed to accept crystals with frequency
from 9.375MHz to 14.0625MHz.
Crystal Oscillator Parameters for ASK Operation
Figure 4 shows a reference oscillator circuit
configuration for ASK operation. The reference oscillator
is capable of driving crystals with ESR range from 20Ω
to 300Ω.
When the ESR of crystal is at 20Ω, the crystal parameter
limits are:
• ESR 20Ω
• Cpar 2 to 10pF
• Cmo 10 to 40fF
CRYSTAL MODEL
ESR
CMO
CPAR
CLOAD
CLOAD
XTLOUT
VSS
MICRF113
When the ESR of crystal is at 300Ω, the crystal
parameter limits are:
• ESR 300Ω
• CPAR 2 to 5pF
• CMO 10 to 40fF
• CLOAD 10 to 30pF
PLL ×32
The function of PLL×32 is to provide a stable carrier
frequency for transmission. It is a “divide by 32” phase
locked loop oscillator.
Power Amplifier
The power amplifier serves two purposes: 1) to buffer
the VCO from external elements and 2) to amplify the
phase locked signal. The power amplifier can produce
+10dBm at 3V (typical).
Enable Control
Enable control gates the ASK data. It only allows
transmission when Lock, Amplitude and Under Voltage
Detect conditions are valid.
Undervoltage Detect
“Undervoltage detect” block senses operating voltage. If
the operating voltage falls below 1.6V, “undervoltage
detect” block will send a signal to “enable control” block
to disable the PA.
XTLIN
MICRF113 ASK
Figure 4. Reference Oscillator ASK Operation
November 2010
11
M9999-112310
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